1. Field of the Invention
This invention relates to a panel shutter assembly which is used for closing and opening an entry to a building, a window, etc.
2. Description of the Prior Art
There is known a panel shutter assembly which comprises a plurality of shutter panels suspended from chains meshing with sprockets for raising and lowering the panels to open and close a shutter opening automatically. This type of shutter has been drawing much attention as having outstanding fireproofness.
The known panel shutter assembly is constructed as shown by way of example in FIGS. 16 to 18. It includes a pair of upstanding guide rails 1 provided along the two vertical edges, respectively, of a shutter opening as defined by an entry to a building, or a window, as shown in FIG. 16. Each guide rail 1 comprises a channel-shaped member defining a panel guide groove and the panel guide grooves of the two guide rails 1 face each other. A panel housing 2 is mounted above the guide rails 1.
The panel housing 2 has a bottom opening located above the guide rails 1. The housing 2 contains a pair of panel driving sprockets 3 located above the guide rails 1, respectively, and near the top of the housing 2, and a pair of panel supporting rails 4 lying in parallel to each other and each having a front end situated near the crest of one of the sprockets 3, extending away from it, and gradually inclined downwardly toward its rear end, as shown in FIG. 17.
A pair of chains 5 mesh with the sprockets 3, respectively, and are movable in the guide rails 1, respectively, in the housing 2 and about the sprockets 3, respectively, to the panel supporting rails 4, respectively. The chains 5 are of the usual construction and are slidably fitted in the guide rails 1, respectively. A plurality of vertically adjoining shutter panels 6 and 7 are suspended from the chains 5 which support each panel at the top corners thereof. Each chain 5 has a plurality of long pins P each serving also as a link pin extending through a link joint and each panel 6 or 7 is rotatably suspended from a pair of long pins P connected to its top corners, respectively. Each pin P carries a guide roller R which can be transferred onto one of the panel supporting rails 4 and roll on it when each panel is withdrawn for suspension from the rails 4, as will hereinafter be described in further detail.
Each panel 6 or 7 is constructed as shown in FIG. 17. Panels as shown in FIG. 19 are also known.
Referring first to FIG. 17, each panel 6 or 7 has a projection 8 extending along its top edge and a recess 9 extending along its bottom edge. The projection 8 of one panel 7 is adapted for fitting in the recess 9 of another panel 6, so that no clearance may be formed between any two adjoining panels 6 and 7 when the shutter is in its fully closed position in which all the panels 6 and 7 stay in a vertically adjoining relation to one another between the guide rails 1.
When the shutter is opened, the panels are raised into the housing 2, and moved horizontally past the sprockets 3 to be suspended from the panel supporting rails 4 one after another. If a lower panel 7 has its projection 8 remaining fitted in the recess 9 of an upper panel 6 as shown in FIG. 18, however, the upper panel 6 cannot be moved horizontally in the housing 2. Therefore, every two vertically adjoining panels 6 and 7 are so supported on the chains 5 as to have a gap L therebetween, so that the projection 8 of the lower panel 7 may be kept disengaged from the recess 9 of the upper panel 6 and thereby allow the upper panel 6 in the housing 6 to be horizontally moved toward the panel supporting rails 4, as shown in FIG. 17.
Referring now to FIG. 19, each panel 6 or 7 has a projection 8 extending along its bottom edge and a recess 9 extending along its top edge, as opposed to each panel 6 or 7 shown in FIG. 17. The recess 9 of each panel is defined by an overlapping extension 9a rising from the top of the panel on its front side and an overlapping extension 8a depends from the bottom of each panel on its rear side, so that when two panels 6 and 7 are joined, the projection 8 of the upper panel 6 may stay between its overlapping extension 8a and the overlapping extension 9a of the lower panel 7, as shown in FIG. 19. The overlapping extensions 8a and 9a serve to close any gap that is required between every two vertically adjoining panels to allow the upper panel 6 in the housing 2 to be moved horizontally toward the panel supporting rails 4.
Referring to the closing of the shutter, the sprockets 3 are rotated counterclockwise, as viewed in FIG. 17 or 19, to move the chains 5 in the same direction. As the chains 5 are moved, the panels 6 and 7 are moved along the panel supporting rails 4 toward the sprockets 3. As the sprockets 3 are further rotated, the panels 6 and 7 are moved past the sprockets 3 and lowered along the guide rails 1 one after another.
No engagement between the projection 8 and the recess 9 occurs between any two vertically adjoining panels until the lowermost panel reaches the ground, whether the panels may be of the type shown in FIGS. 17 or 19. If the lowermost panel reaches the ground, the engagement between the projection 8 and the recess 9 occurs between the lowermost panel and another panel following it immediately, whereby the gap between the two adjoining panels 6 and 7 is closed. As the panels are lowered one after another, such engagement occurs to one pair of vertically adjoining panels after another until the gap between every two vertically adjoining panels is closed when all the panels 6 and 7 have been lowered between the guide rails 1 to bring the shutter to its fully closed position.
When it is desired that the shutter be opened, the sprockets 3 are rotated in the opposite direction to cause the chains 5 to raise the panels 6 and 7 one after another. As the panels are raised into the housing 2 one after another, the disengagement between the projection 8 and the recess 9 occurs to one pair of vertically adjoining panels after another. Therefore, each panel 6 or 7 having its top edge raised to the area between the sprockets 3 can smoothly be moved horizontally past the sprockets 3 to the panel supporting rails 4. As each panel is moved horizontally, the guide rollers R ride on the panel supporting rails 4, so that all the panels 6 and 7 are eventually suspended from the rails 4 in parallel to one another.
It is, however, necessary that the gap L be present between each pair of vertically adjoining panels 6 and 7 including the upper panel 6 that has been raised into the housing 2, to enable the horizontal movement of the upper panel 6 toward the panel supporting rails 4 when the shutter is opened, as hereinbefore stated. The presence of the gap L is likely to present a number of problems, as will hereinafter be pointed out.
Although the gap L shown in FIG. 17 is closed between one pair of vertically adjoining panels 6 and 7 after another as the panels are lowered along the guide rails 1 one after another when the shutter is closed, the gap L remains open between any two vertically adjoining panels until the lower thereof rests on the ground or another panel. Therefore, it is likely that a finger or fingers may get caught in the gap L and hurt, or that anything else may be trapped in the gap L.
If the panels 6 and 7 are of the type as shown in FIG. 19, the gap L between every two vertically adjoining panels remains closed by the overlapping extensions 8a and 9a, and it is, therefore, unlikely that a finger, or anything else may be caught in the gap L. The overlapping extensions 8a and 9a, however, make each panel more complicated in construction and therefore more expensive. Moreover, they add to the height of each panel and thereby the height of the panel housing 2, too. This brings about a great limitation to the place in which the shutter including the panels of the type as shown in FIG. 19 can be installed.